<?php
class cnjmd5{
	
	function cnjmd5(){
		
	}
	
	function get_rnd_iv($iv_len)
	{
	    $iv = '';
	    while ($iv_len-- > 0) {
	        $iv .= chr(mt_rand() & 0xff);
	    }
	    return $iv;
	}
	
	function cnjmd5_encrypt($plain_text, $password, $iv_len = 16)
	{
	    $plain_text .= "\x13";
	    $n = strlen($plain_text);
	    
	    if ($n % 16) {
	    	$plain_text .= str_repeat("\0", 16 - ($n % 16));
	    }
	    
	    $i = 0;	    
	    $enc_text = $this->get_rnd_iv($iv_len);
	    $iv = substr($password ^ $enc_text, 0, 512);
	    
	    while ($i < $n) {
	        $block = substr($plain_text, $i, 16) ^ pack('H*', md5($iv));
	        $enc_text .= $block;
	        $iv = substr($block . $iv, 0, 512) ^ $password;
	        $i += 16;
	    }
	    
	    return base64_encode($enc_text);
	}
	
	function cnjmd5_decrypt($enc_text, $password, $iv_len = 16)
	{
	    $enc_text = base64_decode($enc_text);
	    $n = strlen($enc_text);
	    $i = $iv_len;
	    $plain_text = '';
	    $iv = substr($password ^ substr($enc_text, 0, $iv_len), 0, 512);
	    
	    while ($i < $n) {
	        $block = substr($enc_text, $i, 16);
	        $plain_text .= $block ^ pack('H*', md5($iv));
	        $iv = substr($block . $iv, 0, 512) ^ $password;
	        $i += 16;
	    }
	    
	    return preg_replace('/\\x13\\x00*$/', '', $plain_text);
	}
}


?> 
